Muscle Contraction and Band Changes — NEET Biology
✅ Asked in NEET 2022This pulls the attached actin filaments towards the centre of 'A band. The 'Z' line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere, i.e., contraction. It is clear from the above steps, that during shortening of the muscle, i.e., contraction, the I bands get reduced, whereas the 'A' bands retain the length. The myosin, releasing the ADP and Pi goes back to its relaxed state. A new ATP binds and the cross-bridge is broken. The ATP is again hydrolysed by the myosin head and the cycle of cross bridge formation
During muscle contraction, the I bands shorten because Z lines move toward each other as actin filaments slide over myosin. However, the A band length remains constant because it spans the entire myosin filament, which doesn't change length. Students commonly mistake this, thinking all bands shorten equally. The key trap: confusing I band contraction with A band behavior. Remember: A bands stay fixed (they represent myosin length), while I bands decrease. This is tested repeatedly because understanding sliding filament mechanism requires grasping which structures actually move and which remain static during contraction.
This paragraph was tested 2 times in NEET.
According to the sliding filament theory [NEET Re-2022]
During muscular contraction which of the following events occur? a) 'H' zone disappears b) 'A' band widens c) 'I' band reduces in width d) Myosine hydrolyzes ATP, releasing the ADP and Pi. e) Z-lines attached to actins are pulled inwards. Choose the correct answer from the options given below:
Through deep analysis of NEET and NTA, 88 of 90 questions from the NEET 2026 paper were matched straight from the MedicNEET Biology question bank.
88/90MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.